1. Field of the Invention
The present invention relates to a dish washing machine, and more particularly, to a drive unit for dish washing machines that can be easily assembled and is capable of improving wash water filtering performance.
2. Discussion of the Related Art
Generally, a dish washing machine is a machine that injects wash water to dishes to wash the dishes, and heats the washed dishes to dry the washed dishes. A conventional dish washing machine is illustrated in FIG. 1. The construction of the conventional dish washing machine will be described hereinafter with reference to FIG. 1.
As illustrated in FIG. 1, the conventional dish washing machine comprises: upper and lower injection arms 4 and 5; upper and lower racks 6 and 7; and a drive unit 10, all of which are mounted in a tub 1. To the drive unit 10 are connected upper and lower connection pipes 2 and 3 for pumping out wash water and a drain hose 9 for draining the wash water. The upper and lower connection pipes 2 and 3 are connected to the upper and lower injection arms 4 and 5, respectively. The upper rack 6 is disposed above the upper injection arm 4, and the lower rack 7 is disposed above the lower injection arm 5.
The upper and lower injection arms 4 and 5 are rotatably disposed above the drive unit 10. Each of the upper and lower injection arms 4 and 5 has injection holes for allowing wash water to be injected to the corresponding rack therethrough. In addition, the lower injection arm 5 has injection holes for allowing wash water to be injected therethrough to remove food particles from a filter of the drive unit.
The drive unit 10 will now be described in detail with reference to FIG. 2. The drive unit 10 comprises: a sump 20 for receiving wash water; a heater 30 mounted to the sump 20 for heating wash water; a washing pump mounted to the sump 20 for pumping out wash water; a drain pump mounted to the sump 20 for draining wash water; and filtering device for guiding some of the pumped-out wash water to the upper and lower injection arms 4 and 5 and filtering the remainder of the pumped-out wash water.
The sump 20 has a wash water receiving space 21 for substantially receiving wash water defined therein. Also, the sump 20 has a drain chamber 22, which is partitioned from the wash water receiving space 21. To the outside of the wash water receiving space 21 is mounted a flow channel control device 25. To the flow channel control device 25 a flow channel control valve 26 is connected via a shaft. Also, the sump 20 has a plurality of bosses 29, to which the filtering device is fixed by fixing members.
The washing pump comprises: a washing motor 41 disposed below the sump 20 for generating a driving force; and an impeller 42 mounted in the filtering device for pumping out wash water. The impeller 42 is connected to a shaft of the washing motor 41. The drain pump is mounted to the drain chamber 22 of the sump 20. The drain pump comprises a drain motor 51 and a drain impeller 52.
The filtering device comprises: a pump housing 60 having a space for allowing the impeller 42 to be mounted therein; a filter housing 70 mounted for covering the top of the pump housing 60; and a cover 80 mounted for covering the top of the filter housing 70 and the top of the sump 20. The pump housing 60 is disposed at the lower surface of the filter housing 70. The cover 80 is disposed at the upper surface of the filter housing 70.
The filter housing 70 has a solid waste chamber 75 defined therein. The solid waste chamber 75 has an outlet port 75a, which communicates with the drain chamber 22. The outlet port 75a extends a predetermined length downward from the solid waste chamber 75 such that the outlet port 75a can be inserted into the drain chamber 22.
The cover 80 has a filter 81, which corresponds to the solid waste chamber 75 of the filter housing 70. At the cover, around the filter 81, are formed a plurality of collection holes 82. The collection holes 82 communicate with the sump 20.
The assembly of the drive unit 10 will now be described. At the edge of the pump housing 60 are formed a plurality of bosses 67. At the filter housing 70 are formed a plurality of fixing holes 77, which correspond to the bosses 67 of the pump housing 60, respectively. The fixing holes 77 of the filter housing 70 are arranged along a circumferential part, which is spaced a predetermined distance from the edge of the filter housing 70 toward the center of the filter housing 70. The bosses 67 have fixing holes formed therein, respectively. Consequently, the pump housing 60 is fixed to the filter housing 70 by inserting fixing members B1 into the fixing holes of the bosses 67 of the pump housing 60 through the fixing holes 77 of the filter housing 70, respectively.
At the edge of the filter housing 70 are also formed a plurality of bosses 78, which extend outward from the edge of the filter housing 70. At the cover 80 are formed a plurality of fixing holes 88, which correspond to the bosses 78 of the filter housing 70, respectively. The bosses 78 have fixing holes formed therein, respectively. Consequently, the filter housing 70 is fixed to the cover 80 by inserting fixing members B2 into the fixing holes of the bosses 78 of the filter housing 70 through the fixing holes 88 of the cover 80, respectively.
At the cover 80 are also formed a plurality of fixing holes 89, which correspond to the bosses 29 of the sump 20, respectively. Consequently, the cover 80 is fixed to the sump 20 by inserting fixing members B3 into fixing holes formed in the bosses 29 of the sump 20 through the fixing holes 89 of the cover 80, respectively. Since the cover 80 is supported by the sump 20, the pump housing 60 and the filter housing 70 do not fall. In this way, fixing between the pump housing 60 and the filter housing 70, between the filter housing 70 and the cover 80, and between the cover 80 and the sump 20 is accomplished by means of the fixing members B1, B2 and B3.
The filter housing 70 will now be described in detail with reference to FIG. 3. As shown in FIG. 3, the filter housing 70 comprises: a wash water inlet port 72 for allowing wash water pumped out from the impeller 42 to be introduced therethrough; main flow channels 73a and 73b and a sampling flow channel 74 connected to the wash water inlet port 72; and a solid waste chamber 75 connected to the sampling flow channel 74. At the outlet port 75a of the solid waste chamber 75 is mounted an opening/closing valve for allowing wash water and food particles to be discharged from the solid waste chamber 75 to the drain chamber 22 when a draining operation is performed.
At the wash water inlet port 72 of the filter housing 70 is rotatably mounted a flow channel control valve 26 for opening or closing the main flow channels 73a and 73b. The flow channel control valve 26 is connected to the flow channel control device 25, which is mounted to the sump 20, via a shaft. At the edge of the channel control valve 26 is formed an opening/closing rib 26a for opening or closing the main flow channels 73a and 73b. 
The operation of the dish washing machine with the above-stated construction will now be described. The dish washing machine successively or selectively performs a preliminary washing operation, a main washing operation, a rinsing operation, a heating and rinsing operation, and a drying operation to wash dishes. Draining operations are performed between the respective operations. Hereinafter, the main washing operation will be described in detail.
When the main washing operation is initiated, the washing motor 41 is rotated, and therefore, the impeller 42 is rotated. The impeller 42 pumps out wash water (containing a detergent) from the sump 20 to the wash water inlet port 72 of the pump housing 60. At this time, the flow channel control device 25 is rotated, and therefore, the flow channel control valve 26 either selectively opens the main flow channels 73a and 73b, as shown in FIG. 5A, or simultaneously opens the main flow channels 73a and 73b, as shown in FIG. 3. As a result, some of the wash water in the wash water inlet port 72 is introduced into the upper injection arm 4 and/or the lower injection arm 5 through the main flow channel 73a and/or the main flow channel 73b, and the remainder of the wash water is introduced into the solid waste chamber 75 through the sampling flow channel 74.
Preferably, the flow channel control valve 26 simultaneously or alternately opens the main flow channels 73a and 73b such that the wash water can be supplied to not only the upper injection arm 4 but also the lower injection arm 5. At this time, some of the wash water is always introduced into the sampling flow channel 74 irrespective of which main flow channel(s) is opened by the flow channel control valve 26.
The wash water introduced into the sampling flow channel 74 is directly guided into the solid waste chamber 75. The wash water guided into the solid waste chamber 75 overflows through the filter 81, which is disposed above the solid waste chamber 75. At this time, the filter 81 filters the wash water such that foreign matter is separated from the wash water.
The filtered wash water and the wash water dropping from the upper and lower injection arms 4 and 5 is introduced again into the sump 20 through the collection holes 82 of the cover 80. In this way, the wash water is filtered. It should be noted that some of the wash water is not filtered for a short period of time, but almost all of the wash water is filtered during the main washing operation.
After the washing operation is completed as described above, a draining operation is initiated. When the draining operation is initiated, the drain pump 51 and 52 are operated. At this time, the wash water and the food particles are introduced into the drain pump 51 and impeller 52 from the sump 20 by a suction force of the drain pump 51 and impeller 52. At the same time, the wash water and the food particles are introduced into the drain pump 51 and impeller 52 from the solid waste chamber 75 through the outlet port 75a, as shown in FIG. 5B. The wash water and the food particles introduced into the drain pump 51 and impeller 52 are drained out of the dish washing machine through the drain hose 9.
However, the conventional dish washing machine has the following problems. First, the pump housing is not supported by the sump. The pump housing is fixed to the lower part of the filter housing. As a result, the fixing operation of the impeller to the shaft of the washing motor is very complicated, and therefore, time required to assemble the drive unit is increased.
Secondly, the assembly of the pump housing and the filter housing is accomplished by fixing members. After that, the assembly of the cover and the sump is accomplished by fixing members. As a result, the assembly of the drive unit is very complicated, and the number of fixing members is considerably increased.
Thirdly, the assembly of the pump housing and the filter housing is accomplished by fixing members, and the assembly of the filter housing and the cover is accomplished by fixing members, which are different from those used to assemble the pump housing and the filter housing. As a result, gaps are created between the pump housing and the filter housing and between the filter housing and the cover if the assembly of the pump housing and the filter housing and/or the assembly of the filter housing and the cover is not secure. Consequently, wash water leaks from the gaps created between the pump housing and the filter housing and between the filter housing and the cover, and therefore, wash water pumping performance is decreased. Furthermore, it is necessary to increase the capacity of the washing pump. Consequently, the size of the dish washing machine is increased, and therefore, the manufacturing costs of the dish washing machine are also increased.
Fourthly, the installation space for the solid waste chamber is seriously restricted due to the various flow channels of the filter housing. Consequently, filtering capacity is reduced, and the degree of freedom for installation of the solid waste chamber is decreased. Fifthly, the bottom surface of the solid waste chamber is horizontally disposed. Consequently, solid waste, such as food particles, remains in the solid waste chamber.